Example embodiments of the inventive concept relate to a system and a method for treating a substrate, and in particular, to a system and a method for cleaning a substrate.
In general, a semiconductor device is fabricated by performing various processes (e.g., a photolithography process, an etching process, an ion implantation process, and a deposition process) on a substrate (e.g., a silicon wafer).
In each process, various foreign substances (e.g., particles, organic contaminants, and metallic impurities) may be produced. The foreign substances may lead to process defects in a subsequent process of treating a substrate and thereby deterioration in performance and yield of a semiconductor device, and thus, in a process of fabricating a semiconductor device, it is necessary to perform a cleaning process for removing such foreign substances.
The cleaning process may include a chemical treating process of removing contaminants from a surface of a substrate using chemicals, a wet cleaning process of removing remaining chemicals from the surface of the substrate using pure or de-ionized water, and a drying process of supplying dehydration fluid on the surface of the substrate to remove remnants of the pure water.
In the past, the drying process was performed in such a way to supply heated nitrogen gas on a substrate, on which pure water remains. However, a reduction in line width or an increase in aspect ratio of patterns led to a great difficulty in removing the pure water from narrow gaps between the patterns. To overcome this problem, in a recent drying process, the pure water remaining on a substrate is replaced with liquid organic solvent (e.g., isopropyl alcohol) that have high volatility and low surface tension, compared with the pure water, and then, heated nitrogen gas is supplied to dry the substrate.
However, there is a difficulty in mixing non-polar organic solvent with polar water, and thus, in order to replace the pure water with the liquid organic solvent, it is necessary to supply a large amount of liquid organic solvent onto the substrate for a long time.
However, although the organic solvent is used for the drying process, it is difficult to avoid the problem of pattern collapse in sub-30 nm semiconductor devices. Recently, a process of drying a substrate using supercritical fluid is recently being developed as an alternative to such conventional drying processes.